Activation of the full length, membrane bound isoform of the Receptor for Advanced Glycation End Products (flRAGE) on blood brain barrier (BBB) endothelium, neurons and microglia promotes the onset and progression of Alzheimer's Disease (AD) by increasing accumulation of beta-amyloid ( 2) in brain tissue, raising inflammation and elevating oxidative stress. Although preventing activation of flRAGE by antagonizing binding to its many ligands is an attractive AD treatment strategy, toxicity, low efficacy and poor BBB penetration have limited RAGE-targeted therapeutic testing to one small molecule and even this lone drug candidate caused side effects. Wewill develop proteolytic antibodies (CatAbs), able to inactivate thousands of flRAGE molecules per CatAb, as a new class of catalytically advantaged therapeutics with the potential to serve as the first effective disease-modifying treatments for AD. A yeast surface display platform, previously used to develop antigen-binding Abs (BindAbs) to treat a range of diseases, will be employed to create human CatAbs catalyzing specific hydrolysis of flRAGE. flRAGE CatAbs' ability to catalyze thousands of cycles of short-lived flRAGE binding, flRAGE hydrolysis, product release and interaction with another flRAGE molecule give CatAbs many catalytic advantages over flRAGE-binding drugs. CatAbs' specificity and high dose efficacy reduces the chances of side effects as seen in the flRAGE antagonist trial above. Also, CatAbs pair BindAbs' specificity with a much higher number of targets inactivated per Ab, a key benefit given the BBB's low permeability to protein drugs. Furthermore, CatAbs' rapid hydrolysis and release of flRAGE molecules will allow inactivation of flRAGE targets expressed after drug administration, giving CatAbs a unique ability to account for flRAGE turnover. Finally, unlike flRAGE antagonists, CatAbs will not undergo long-lived binding to flRAGE's circulating isoform, sRAGE, and thus be unlikely to impede sRAGE-promoted clearance of Ab from plasma. We will use a novel library design approach to construct a yeast-displayed CatAb library that will serve as a source of multiple flRAGE CatAbs. Fluorescence Activated Cell Sorting (FACS) will enable both isolation of lead flRAGE CatAbs and subsequent CatAb engineering for enhanced catalytic properties. CatAb hydrolysis of flRAGE expressed on murine cell membranes will be validated in vitro. This work will lead to proposals for follow on CatAb engineering and AD mouse model studies performed in collaboration with the Sun Health Research Institute Neuroinflammation Laboratory (Sun City, AZ). We are excited about the potential impact of these first-ever catalytically advantaged AD therapeutics and are eager to initiate this research.